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Aquatic Warbler Acrocephalus paludicola

Justification
Surveys in 1995-2005 discovered previously unknown populations of this species, resulting in a substantially increased population estimate. However, it probably declined rapidly until the late 1990s, as a result of the destruction of its habitat, at a rate equivalent to 40% in 10 years. It therefore qualifies as Vulnerable. The decline in the central-European core population has recently been stopped owing to intensive management and conservation projects, but the population is still widely conservation-dependent. The genetically distinct and isolated Pomeranian population is still declining and at a critical level, while the population in Hungary recently declined to extinction, and that in Lithuania continues to decline.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.

Identification
12-13 cm. Small, heavily streaked, buff-and-black warbler. Strong black streaking on mantle bordered by pale "tramlines". Pale coronal stripe with black border. Pale lores. Streaked back, rump and uppertail-coverts. Finely streaked breast. Similar spp. Sedge Warbler A. schoenobaenus generally browner and less streaked. Lacks strongly streaked mantle and pale "tramlines", pale coronal stripe and streaks on breast. Song more complex and varied with mimicry and distinctive sweet notes. Voice Series of simple trills and short whistles, given from vegetation or short song flight. Does not mimic extensively. Low tuk or dry churr call.

Distribution and population
Acrocephalus paludicola breeds across a highly fragmented range at fewer than 50 regular breeding sites in the following countries, with numbers given of singing males between 2002 and 2011: Poland, 2,670-3,850; Belarus, 3,940-6,300; Ukraine, 2,000-4,600; Germany, fewer than 25, and Lithuania, 110-309 (M. Flade and L. Lachmann in litt. 2007, U. Malashevich in litt. 2012). On migration, it has been recorded in c.15 European countries, mainly in the west and southwest of the continent (U. Malashevich in litt. 2012). It winters in the Sahelian belt of sub-Saharan West Africa, mainly along the lower Senegal River, where it was discovered in January 2007 within and to the north of Djoudj National Park (Bargain et al. 2008, Flade 2008, U. Malashevich in litt. 2012), and in 2011 found in smaller wetlands in south-west Mauritania and at the inner Niger Delta in Mali (U. Malashevich in litt. 2012). Two-thirds of the known population has been discovered since 1995, and the total population is estimated at 12,100-14,700 singing males. Since 1970, it is likely to have declined significantly as a result of the destruction of 80-90% of its habitat in the river systems of upper Pripyat, Yaselda (Belarus) and Biebrza/Narew (Poland). These systems hold approximately 75% of the European population. Owing to extensive conservation projects, the decline has been stopped in its central European strongholds in eastern Poland, Belarus and Ukraine, but continues in the Pomeranian population of northwest Poland and northeast Germany. In Hungary, the population collapsed in 2002-2007. The tiny Siberian population is on the brink of extinction and has probably already disappeared, in which case the species has become a European endemic breeder (M. Flade and L. Lachmann in litt. 2007).

Population justification
The population is estimated at 11,000-16,000 singing males (M. Flade in litt. 2012), equivalent to 22,000-32,000 mature individuals or 33,000-48,000 individuals in total.

Trend justification
This species probably declined rapidly until the late 1990s, as a result of the destruction of its habitat at a rate equivalent to 40% in ten years. The decline in the central European core population has recently been stopped owing to intensive management and conservation projects but other populations continue to decline through habitat loss and degradation.

Ecology
It breeds in large open lowland marsh habitats with low grassy vegetation (mostly sedge fen mires) with water mostly less than 10 cm deep (Aquatic Warbler Conservation Team 1999). It winters in similar habitats (the grassy saline Scirpus, Eleocharis and Oryza marshes of the Senegal and Niger deltas) and, on migration, favours coastal habitats with low stands of sedge and reed near open water (Flade et al. 2011).

Threats
The most important threats are loss of breeding habitat owing to drainage for agriculture and peat extraction, damming of floodplains, unfavourable water management and the canalisation of rivers. Habitat degradation is widespread where traditional fen management has ceased allowing succession to unsuitable overgrown reedbed, scrub or woodland (Aquatic Warbler Conservation Team 1999). Commercial reed cutting can maintain suitable breeding habitat for the species in central Europe, but this is threatened by changes that are likely to occur along with the implementation of the Common Agricultural Policy (Tanneberger et al. 2009). Uncontrolled fires in spring and summer pose a direct threat to birds and nests, and can burn out the upper peat layer of fens (Aquatic Warbler Conservation Team 1999). In the wintering grounds, agricultural cultivation and irrigation (creation of rice and sugar cane plantations), drought, wetland drainage, intensive grazing, succession to scrub, desertification and salinisation of irrigated soils are all potential threats (Aquatic Warbler Conservation Team 1999, M. Flade and L. Lachmann in litt. 2007).


Conservation Actions Underway
CMS Appendix I and II. It is legally protected in all countries of its breeding range except Ukraine and Russia (U. Malashevich in litt. 2012). All key breeding sites in Belarus, Germany, Hungary and Poland are located within protected areas (Aquatic Warbler Conservation Team 1999, U. Malashevich in litt. 2012). Habitat is actively managed in Poland, Belarus, Ukraine, Lithuania, Hungary and Germany. All breeding range states but Russia have monitoring programmes (Aquatic Warbler Conservation Team 1999, M. Flade and L. Lachmann in litt. 2007). A study to identify the wintering range of the species was conducted in 2007 (Flade 2008). Studies on halting succession have been conducted in Belarus, Poland and Ukraine (M. Kalyakin in litt. 1999). A European action plan was published in 1996 and updated in 1998, 2003 and 2008 (Flade and Lachmann 2008). The species was put into agenda of the Conference of Parties for the CMS in November 2011, where a special resolution on African-Eurasian landbirds was adopted, which applies to Aquatic Warbler (U. Malashevich in litt. 2011).
Conservation Actions Proposed
Implement a monitoring programme in Russia. Protect key breeding sites and develop management plans. Promote protection of the species and its habitat in wintering areas and along the migration route. Ensure full legal protection.

Related state of the world's birds case studies

References
Aquatic Warbler Conservation Team. 1999. World population, trends and conservation status of the Aquatic Warbler Acrocephalus paludicola. Vogelwelt 120: 65-85.

Bargain, B.; Le Nevé, A.; Guyot, G. 2008. Première zone d'hivernage du Phragmite aquatique Acrocephalus paludicola découverte en Afrique. Ornithos 15(6): 411-425.

Flade, M. 2008. Searching for wintering sites of the Aquatic Warbler Acrocephalus paludicola in Senegal 18th January - 10th February 2007: final report.

Flade, M.; Diop, I.; Haase, M.; Le Nevé, A.; Oppel, S.; Tegetmeyer, C.; Vogel, A.; Salewski, V. 2011. Distribution, ecology and threat status of the Aquatic Warblers Acrocephalus paludicola wintering in West Africa. Journal of Ornithology 152(supplement 1): 129-140.

Heredia, B. 1996. Action plan for the Aquatic Warbler (Acrocephalus paludicola) in Europe. In: Heredia, B.; Rose, L.; Painter, M. (ed.), Globally threatened birds in Europe: action plans, pp. 327-338. Council of Europe, and BirdLife International, Strasbourg.

Kozulin, A.; Flade, M. 1999. Breeding habitat, abundance and threat status of the Aquatic Warbler Acrocephalus paludicola in Belarus. Vogelwelt 120: 97-111.

Tanneberger, F.; Tegetmeyer, C.; Dylawerski, M.; Flade, M.; Joosten, H. 2009. Commercially cut reed as a new and sustainable habitat for the globally threatened Aquatic Warbler. Biodiversity and Conservation 18: 1475-1489.

Further web sources of information
Action Plan for the Aquatic Warbler in Europe

Convention on Migratory Species (CMS) Memorandum of Understanding and Conservation Plan

Detailed species account from Birds in Europe: population estimates trends and conservation status (BirdLife International 2004)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Explore HBW Alive for further information on this species

View photos and videos and hear sounds of this species from the Internet Bird Collection

Text account compilers
Capper, D., Derhé, M., Ekstrom, J., Peet, N., Symes, A. & Khwaja, N.

Contributors
Flade, M., Kalyakin, M., Lachmann, L., Malashevich, U. & Burfield, I.

Recommended citation
BirdLife International (2014) Species factsheet: Acrocephalus paludicola. Downloaded from http://www.birdlife.org on 26/10/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/10/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Aquatic warbler (Acrocephalus paludicola) 0

Key facts
Current IUCN Red List category Vulnerable
Family Sylviidae (Old World warblers)
Species name author (Vieillot, 1817)
Population size 22000-32000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 183,000 km2
Country endemic? No
Links to further information
- Additional Information on this species